#-*- coding:utf-8 _*-
"""
@author:fxw
@file: vgg.py
@time: 2020/07/24
"""
import torch
import torch.nn as nn
import torch.utils.model_zoo as model_zoo


__all__ = [
    'VGG', 'vgg11', 'vgg11_bn', 'vgg13', 'vgg13_bn', 'vgg16', 'vgg16_bn',
    'vgg19_bn', 'vgg19',
]


model_urls = {
    'vgg11': 'https://download.pytorch.org/models/vgg11-bbd30ac9.pth',
    'vgg13': 'https://download.pytorch.org/models/vgg13-c768596a.pth',
    'vgg16': 'https://download.pytorch.org/models/vgg16-397923af.pth',
    'vgg19': 'https://download.pytorch.org/models/vgg19-dcbb9e9d.pth',
    'vgg11_bn': 'https://download.pytorch.org/models/vgg11_bn-6002323d.pth',
    'vgg13_bn': 'https://download.pytorch.org/models/vgg13_bn-abd245e5.pth',
    'vgg16_bn': 'https://download.pytorch.org/models/vgg16_bn-6c64b313.pth',
    'vgg19_bn': 'https://download.pytorch.org/models/vgg19_bn-c79401a0.pth',
}


class VGG(nn.Module):

    def __init__(self, features, num_classes=1000, init_weights=True):
        super(VGG, self).__init__()
        self.features = features
        if init_weights:
            self._initialize_weights()

    def forward(self, x):
        x = self.features(x)
        return x

    def _initialize_weights(self):
        for m in self.modules():
            if isinstance(m, nn.Conv2d):
                nn.init.kaiming_normal_(m.weight, mode='fan_out', nonlinearity='relu')
                if m.bias is not None:
                    nn.init.constant_(m.bias, 0)
            elif isinstance(m, nn.BatchNorm2d):
                nn.init.constant_(m.weight, 1)
                nn.init.constant_(m.bias, 0)
            elif isinstance(m, nn.Linear):
                nn.init.normal_(m.weight, 0, 0.01)
                nn.init.constant_(m.bias, 0)


def make_layers(cfg, is_gray=False,batch_norm=False):
    layers = []
    in_channels = 3
    if is_gray:
        in_channels = 1
    for v in cfg:
        if v == 'M':
            layers += [nn.MaxPool2d(kernel_size=2, stride=2)]
        elif v=='N':
            layers += [nn.MaxPool2d(kernel_size=2, stride=(2,1))]
        else:
            conv2d = nn.Conv2d(in_channels, v, kernel_size=3, padding=1)
            if batch_norm:
                layers += [conv2d, nn.BatchNorm2d(v), nn.ReLU(inplace=True)]
            else:
                layers += [conv2d, nn.ReLU(inplace=True)]
            in_channels = v
    return nn.Sequential(*layers)


cfg = {
    'A': [64, 'M', 128, 'M', 256, 256, 'N', 512, 512, 'N', 512, 512, 'N'],
    'B': [64, 64, 'M', 128, 128, 'M', 256, 256, 'N', 512, 512, 'N', 512, 512, 'N'],
    'D': [64, 64, 'M', 128, 128, 'M', 256, 256, 256, 'N', 512, 512, 512, 'N', 512, 512, 512, 'N'],
    'E': [64, 64, 'M', 128, 128, 'M', 256, 256, 256, 256, 'M', 512, 512, 512, 512, 'N', 512, 512, 512, 512, 'N'],
}


def vgg11(pretrained=False,is_gray=False, **kwargs):
    """VGG 11-layer model (configuration "A")

    Args:
        pretrained (bool): If True, returns a model pre-trained on ImageNet
    """
    if pretrained:
        kwargs['init_weights'] = False
    model = VGG(make_layers(cfg['A'],is_gray=is_gray), **kwargs)
    if pretrained:
        pretrained_model = model_zoo.load_url(model_urls['vgg11'])
        state = model.state_dict()
        for key in state.keys():
            if key in pretrained_model.keys():
                if (key=='features.0.weight' and is_gray):
                    state[key] = torch.mean(pretrained_model[key],1).unsqueeze(1)
                else:
                    state[key] = pretrained_model[key]
        model.load_state_dict(state)
    return model


def vgg11_bn(pretrained=False,is_gray=False, **kwargs):
    """VGG 11-layer model (configuration "A") with batch normalization

    Args:
        pretrained (bool): If True, returns a model pre-trained on ImageNet
    """
    if pretrained:
        kwargs['init_weights'] = False
    model = VGG(make_layers(cfg['A'], is_gray=is_gray,batch_norm=True), **kwargs)
    if pretrained:
        pretrained_model = model_zoo.load_url(model_urls['vgg11_bn'])
        state = model.state_dict()
        for key in state.keys():
            if key in pretrained_model.keys():
                if (key=='features.0.weight' and is_gray):
                    state[key] = torch.mean(pretrained_model[key],1).unsqueeze(1)
                else:
                    state[key] = pretrained_model[key]
        model.load_state_dict(state)
    return model


def vgg13(pretrained=False,is_gray=False, **kwargs):
    """VGG 13-layer model (configuration "B")

    Args:
        pretrained (bool): If True, returns a model pre-trained on ImageNet
    """
    if pretrained:
        kwargs['init_weights'] = False
    model = VGG(make_layers(cfg['B'],is_gray=is_gray), **kwargs)
    if pretrained:
        pretrained_model = model_zoo.load_url(model_urls['vgg13'])
        state = model.state_dict()
        for key in state.keys():
            if key in pretrained_model.keys():
                if (key=='features.0.weight' and is_gray):
                    state[key] = torch.mean(pretrained_model[key],1).unsqueeze(1)
                else:
                    state[key] = pretrained_model[key]
        model.load_state_dict(state)
    return model


def vgg13_bn(pretrained=False, is_gray=False,**kwargs):
    """VGG 13-layer model (configuration "B") with batch normalization

    Args:
        pretrained (bool): If True, returns a model pre-trained on ImageNet
    """
    if pretrained:
        kwargs['init_weights'] = False
    model = VGG(make_layers(cfg['B'],is_gray=is_gray, batch_norm=True), **kwargs)
    if pretrained:
        pretrained_model = model_zoo.load_url(model_urls['vgg13_bn'])
        state = model.state_dict()
        for key in state.keys():
            if key in pretrained_model.keys():
                if (key=='features.0.weight' and is_gray):
                    state[key] = torch.mean(pretrained_model[key],1).unsqueeze(1)
                else:
                    state[key] = pretrained_model[key]
        model.load_state_dict(state)
    return model


def vgg16(pretrained=False,is_gray=False, **kwargs):
    """VGG 16-layer model (configuration "D")

    Args:
        pretrained (bool): If True, returns a model pre-trained on ImageNet
    """
    if pretrained:
        kwargs['init_weights'] = False
    model = VGG(make_layers(cfg['D'],is_gray=is_gray), **kwargs)
    if pretrained:
        pretrained_model = model_zoo.load_url(model_urls['vgg16'])
        state = model.state_dict()
        for key in state.keys():
            if key in pretrained_model.keys():
                if (key=='features.0.weight' and is_gray):
                    state[key] = torch.mean(pretrained_model[key],1).unsqueeze(1)
                else:
                    state[key] = pretrained_model[key]
        model.load_state_dict(state)
    return model


def vgg16_bn(pretrained=False,is_gray=False, **kwargs):
    """VGG 16-layer model (configuration "D") with batch normalization

    Args:
        pretrained (bool): If True, returns a model pre-trained on ImageNet
    """
    if pretrained:
        kwargs['init_weights'] = False
    model = VGG(make_layers(cfg['D'],is_gray=is_gray, batch_norm=True), **kwargs)
    if pretrained:
        pretrained_model = model_zoo.load_url(model_urls['vgg16_bn'])
        state = model.state_dict()
        for key in state.keys():
            if key in pretrained_model.keys():
                if (key=='features.0.weight' and is_gray):
                    state[key] = torch.mean(pretrained_model[key],1).unsqueeze(1)
                else:
                    state[key] = pretrained_model[key]
        model.load_state_dict(state)
    return model


def vgg19(pretrained=False, is_gray=False,**kwargs):
    """VGG 19-layer model (configuration "E")

    Args:
        pretrained (bool): If True, returns a model pre-trained on ImageNet
    """
    if pretrained:
        kwargs['init_weights'] = False
    model = VGG(make_layers(cfg['E'],is_gray=is_gray), **kwargs)
    if pretrained:
        pretrained_model = model_zoo.load_url(model_urls['vgg19'])
        state = model.state_dict()
        for key in state.keys():
            if key in pretrained_model.keys():
                if (key=='features.0.weight' and is_gray):
                    state[key] = torch.mean(pretrained_model[key],1).unsqueeze(1)
                else:
                    state[key] = pretrained_model[key]
        model.load_state_dict(state)
    return model


def vgg19_bn(pretrained=False, is_gray=False,**kwargs):
    """VGG 19-layer model (configuration 'E') with batch normalization

    Args:
        pretrained (bool): If True, returns a model pre-trained on ImageNet
    """
    if pretrained:
        kwargs['init_weights'] = False
    model = VGG(make_layers(cfg['E'],is_gray=is_gray, batch_norm=True), **kwargs)
    if pretrained:
        pretrained_model = model_zoo.load_url(model_urls['vgg19_bn'])
        state = model.state_dict()
        for key in state.keys():
            if key in pretrained_model.keys():
                if (key=='features.0.weight' and is_gray):
                    state[key] = torch.mean(pretrained_model[key],1).unsqueeze(1)
                else:
                    state[key] = pretrained_model[key]
        model.load_state_dict(state)
    return model

